21968881 has 12 divisors (see below), whose sum is σ = 24667776. Its totient is φ = 19541720.

The previous prime is 21968867. The next prime is 21968899. The reversal of 21968881 is 18886912.

It is not a de Polignac number, because 21968881 - 2⁷ = 21968753 is a prime.

It is a super-2 number, since 2×21968881² = 965263464784322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21969881) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3756 + ... + 7618.

It is an arithmetic number, because the mean of its divisors is an integer number (2055648).

Almost surely, 2^21968881 is an apocalyptic number.

It is an amenable number.

21968881 is a deficient number, since it is larger than the sum of its proper divisors (2698895).

21968881 is a wasteful number, since it uses less digits than its factorization.

21968881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3932 (or 3921 counting only the distinct ones).

The product of its digits is 55296, while the sum is 43.

The square root of 21968881 is about 4687.0972893679. The cubic root of 21968881 is about 280.0717545693.

The spelling of 21968881 in words is "twenty-one million, nine hundred sixty-eight thousand, eight hundred eighty-one".